By Jung Min-hoThe mother of the three-year-old girl who was found dead on Jeju Island on Nov. 4 has also been found dead, police said Thursday.

The Jeju Provincial Police Agency said the mother, 33, a Paju resident whose surname was Jang, was found on the island's northern side about 6:40 p.m. Wednesday.

Previously, investigators confirmed the two took a taxi to an area near a beach on northern Jeju around 2:30 a.m. on Nov. 2. Two days later, the girl's body was found and police began searching for her mother.

An autopsy shows that the girl suffered no external injuries and the most likely cause of death was drowning. It is still unclear whether she inhaled toxic gases, which the National Forensic Service (NFS) will find out later through a second, more through, autopsy.

The NFS's findings are expected to be crucial for police to discover the truth behind their deaths. Investigators said Jang bought charcoal, bottled butane and a lighter on Nov. 1, the day after she and her daughter arrived on Jeju.

Given that there were burn marks on their motel room's bathroom floor, police believe the mother might have attempted to kill herself and her daughter there and made another attempt the next day.

Police also found that the two bought a one-way airplane ticket to the island.

Police carried out an autopsy on the mother's body Thursday and the result is expected in the next few days.